feat: add circuit breaker to github client, improve env var handling

Also changed the error handling, API cache structure, removed some
redundant tests & methods

Author: Xevion

Cargo.lock

@@ -40,6 +40,7 @@ tokio-stream = "0.1.17"
 foyer = { version = "0.18.0", features = ["serde"] }
 bincode = "2.0.1"
 sha256 = "1.6.0"
+failsafe = "1.3.0"
 
 [build-dependencies]
 phf_codegen = "0.12.1"

Cargo.toml

@@ -88,7 +88,7 @@ fn format_svg_template(
 /// Result indicating success or failure of card generation
 pub async fn run(cli: Cli) -> Result<()> {
     let repo_path = cli.repository.as_ref().unwrap();
-    let repo = github::get_repository_info(repo_path, cli.token).await?;
+    let repo = github::GITHUB_CLIENT.get_repository_info(repo_path).await?;
 
     let output_path = match cli.output {
         Some(path) => path,

src/cli.rs

@@ -68,6 +68,10 @@ pub enum GitHubError {
     /// Authentication error
     #[error("Authentication failed: {0}")]
     AuthError(String),
+
+    /// Circuit breaker open
+    #[error("Circuit breaker open")]
+    CircuitBreakerOpen,
 }
 
 /// Image generation specific errors
@@ -147,6 +151,7 @@ impl From<GitHubError> for axum::http::StatusCode {
             GitHubError::NetworkError => axum::http::StatusCode::BAD_GATEWAY,
             GitHubError::InvalidFormat(_) => axum::http::StatusCode::BAD_REQUEST,
             GitHubError::AuthError(_) => axum::http::StatusCode::UNAUTHORIZED,
+            GitHubError::CircuitBreakerOpen => axum::http::StatusCode::SERVICE_UNAVAILABLE,
         }
     }
 }